NOTES ON CRUSTACEA DECAPODA IN THE 

 INDIAN MUSEUM. 



XV. PONTONIINAE. 



By Stanley Kemp, Sc.D., Superintendent, Zoological 

 Survey of India. 



The Pontoniinae form one of the four subfamilies into which 

 the Caridean family Palaemonidae is divided; the other three are 

 the Palaemoninae, the Desmoearidinae and the Typhlocaridinae. 

 Of the very numerous species known in the family all except three 

 belong to the Palaemoninae and Pontoniinae. The Desmoearidinae 

 comprise only a single species, Desmocaris trispinosus (Aurivillius), 

 found in freshwater streams in West Africa, and Sollaud' who first 

 drew attention to its peculiar characters regards it ?s the most 

 primitive known Palaemonid. The Typhlocaridinae include two 

 remarkable blind species, both belonging to the genus Typhlocaris 

 Caiman, 2 which inhabit waters of subterranean origin in Palestine 

 and Cyrenaica. Typhlocaris differs from all other Palaemonidae 

 in the presence of a longitudinal suture in the carapace, resembling 

 that found in certain Penaeidae and in the Thalassinidea. 



The Palaemoninae and Pontoniinae are closely related sub- 

 families, distinguished from the other two by a number of impor- 

 tant characters. 8 They differ from one another in two respects. 

 The pleurobrancli found in the Palaemoninae above the base of 

 the third maxilliped is invariably absent in the Pontoniinae, with 

 the result that six large branchiae are found in the former sub- 

 family as against five in the latter. The telson-tip in the Palae- 

 moninae is usually armed with two pairs of spines and a varying 

 number of plumose setae, whereas in the Pontoniinae there 

 are always three pairs of spines.* This character is not an invaria- 

 ble one. There appears to be no real morphological distinction 

 between spines and setae as found at the apex of the telson ; in 

 the Pontoniinae the median spines are frequently plumose and I 

 have seen one species of Palaemoninae B in which there are three 

 pairs of spines, almost precisely as in the related subfamily. 



1 Sollaud, Compter rendus Acad. Scf. Pan's CI. II, p. 913 (iqn). 



- Caiman, Trans. Linn. Soc. (2) Zool. XI, p. 93 (1909) ; Annandale and 

 Kemp, Jotim. Asint. Soc. Bengal (n.s.) IX, p. 245 (1913) , Parisi, At.i Soc. /fa/. 

 Sri. nat. Milano I. IX, p. 241 (1920). 



s The characters of the four subfamilies are summarized by Borr,?daile, Trans. 

 Linn. Soc. (2) Zool- XVII, p. 326 (1917). 



* Cntttierea is said to possess merely a single pair, but the genus is only known 

 from one specimen. It may prove not to belong to the Pontoniinae. 



6 A remarkable species from South India, allied to Palaemonefes and hitherto 

 undescribed. 



